package org.apache.maven.repository;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;

import org.apache.maven.RepositoryUtils;
import org.apache.maven.artifact.repository.ArtifactRepository;
import org.apache.maven.settings.Mirror;
import org.codehaus.plexus.component.annotations.Component;
import org.codehaus.plexus.util.StringUtils;

@Component(role = MirrorSelector.class)
public class DefaultMirrorSelector implements MirrorSelector {

  private static final String WILDCARD = "*";

  private static final String EXTERNAL_WILDCARD = "external:*";

  public Mirror getMirror(ArtifactRepository repository, List<Mirror> mirrors) {
    String repoId = repository.getId();

    if (repoId != null && mirrors != null) {
      for (Mirror mirror : mirrors) {
        if (repoId.equals(mirror.getMirrorOf()) && matchesLayout(repository, mirror)) {
          return mirror;
        }
      }

      for (Mirror mirror : mirrors) {
        if (matchPattern(repository, mirror.getMirrorOf()) && matchesLayout(repository, mirror)) {
          return mirror;
        }
      }
    }

    return null;
  }

  /**
   * This method checks if the pattern matches the originalRepository. Valid patterns: * =
   * everything external:* = everything not on the localhost and not file based. repo,repo1 = repo
   * or repo1 *,!repo1 = everything except repo1
   *
   * @param originalRepository to compare for a match.
   * @param pattern used for match. Currently only '*' is supported.
   * @return true if the repository is a match to this pattern.
   */
  static boolean matchPattern(ArtifactRepository originalRepository, String pattern) {
    boolean result = false;
    String originalId = originalRepository.getId();

    // simple checks first to short circuit processing below.
    if (WILDCARD.equals(pattern) || pattern.equals(originalId)) {
      result = true;
    } else {
      // process the list
      String[] repos = pattern.split(",");
      for (String repo : repos) {
        // see if this is a negative match
        if (repo.length() > 1 && repo.startsWith("!")) {
          if (repo.substring(1).equals(originalId)) {
            // explicitly exclude. Set result and stop processing.
            result = false;
            break;
          }
        }
        // check for exact match
        else if (repo.equals(originalId)) {
          result = true;
          break;
        }
        // check for external:*
        else if (EXTERNAL_WILDCARD.equals(repo) && isExternalRepo(originalRepository)) {
          result = true;
          // don't stop processing in case a future segment explicitly excludes this repo
        } else if (WILDCARD.equals(repo)) {
          result = true;
          // don't stop processing in case a future segment explicitly excludes this repo
        }
      }
    }
    return result;
  }

  /**
   * Checks the URL to see if this repository refers to an external repository
   *
   * @param originalRepository
   * @return true if external.
   */
  static boolean isExternalRepo(ArtifactRepository originalRepository) {
    try {
      URL url = new URL(originalRepository.getUrl());
      return !(url.getHost().equals("localhost") || url.getHost().equals("127.0.0.1")
          || url.getProtocol().equals("file"));
    } catch (MalformedURLException e) {
      // bad url just skip it here. It should have been validated already, but the wagon lookup will
      // deal with it
      return false;
    }
  }

  static boolean matchesLayout(ArtifactRepository repository, Mirror mirror) {
    return matchesLayout(RepositoryUtils.getLayout(repository), mirror.getMirrorOfLayouts());
  }

  /**
   * Checks whether the layouts configured for a mirror match with the layout of the repository.
   *
   * @param repoLayout The layout of the repository, may be {@code null}.
   * @param mirrorLayout The layouts supported by the mirror, may be {@code null}.
   * @return {@code true} if the layouts associated with the mirror match the layout of the original
   *         repository, {@code false} otherwise.
   */
  static boolean matchesLayout(String repoLayout, String mirrorLayout) {
    boolean result = false;

    // simple checks first to short circuit processing below.
    if (StringUtils.isEmpty(mirrorLayout) || WILDCARD.equals(mirrorLayout)) {
      result = true;
    } else if (mirrorLayout.equals(repoLayout)) {
      result = true;
    } else {
      // process the list
      String[] layouts = mirrorLayout.split(",");
      for (String layout : layouts) {
        // see if this is a negative match
        if (layout.length() > 1 && layout.startsWith("!")) {
          if (layout.substring(1).equals(repoLayout)) {
            // explicitly exclude. Set result and stop processing.
            result = false;
            break;
          }
        }
        // check for exact match
        else if (layout.equals(repoLayout)) {
          result = true;
          break;
        } else if (WILDCARD.equals(layout)) {
          result = true;
          // don't stop processing in case a future segment explicitly excludes this repo
        }
      }
    }

    return result;
  }

}
